FDA grants emergency approval to Swiss firm’s coronavirus antibody test | TheHill

Forum for Healthcare Freedom commentary:

There are two dueling schools of thought in the debate over antibody testing.

One says that antibody testing is the only way to estimate true prevalence of SARS-CoV-2, given the high percentage of mild and asymptomatic cases shown in captive populations such as cruise ships, prisons, etc, and therefore the only way to determine the true mortality rate. But we must have a test with very high sensitivity/specificity in order to interpret these individual tests with a fair degree of confidence.

The other side claims that when/if prevalence of a disease is low, the predictive value of a positive test (PPV) is very low (unless specificity approaches 100% i.e. low chance of false positive)

Both philosophical camps are correct. But as prevalence goes up and if a test has high sensitivity & specificity, then PPV curve goes up steeply.

So, bottom line is, if the Roche test shows no cross reactivity to four common non-SARS Coronaviruses, we can validate the sensitivity (and by extension the PPV) by testing patients that have recovered who had typical symptoms and positive PCR test for SARS-CoV-2.

If this test is truly as good as marketed, time to start getting the data to help us get back to work safely and help guide medical decision-making.

Otherwise, we guess without data.

Roche Holding AG said that its antibody test, Elecsys Anti-SARS-CoV-2, had a 99.8 percent specificity rate and a sensitivity rate of 100 percent based on a sampling of 5,272 people.

Roche said that its sampling showed no cross-reactivity to the four human coronaviruses causing a common cold, reducing the chance of false positives.


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